High power requirements of assistive exoskeletons and the finite energy density of the battery packs significantly limit the battery life of untethered mobile exoskeletons [1]}. Young and Ferris [2]} have reported that the maximum battery life of portable exoskeletons is limited to 5 hours, indicating the need for several charging breaks within a day. Harvesting the dissipated power from assistive exoskeletons can help increase power efficiency of mobile exoskeletons, significantly prolonging their device battery life [1]}, [4]}. Power regeneration and harvesting have been utilized in the literature for several assistive devices and robotic systems with a reported highest regeneration/power harvesting efficiency of 65%, as reviewed in [1]}, [4]}.
